Dense Nonaqueous-Phase Liquids and Flux-Based Site Management

Introduction

Dense Nonaqueous-Phase Liquids and
Flux-Based Site Remediation

DNAPLs are organic liquids with a density greater than water. They include solvents, coal tar, and creosotes. Contamination of groundwater can occur as a result of dissolved plumes generated from DNAPL source zones. DNAPLs pose significant challenges in site remediation.

Field-scale research has demonstrated that a high percentage of nonaqueous-phase liquid (NAPL) mass can be rapidly depleted within source zones by using aggressive in situ remedial technologies, such as thermal treatment or cosolvent flushing. Even with these aggressive technologies, however, the efficiency of NAPL depletion often decays exponentially as NAPL mass is removed from the source; complete NAPL removal may not be technically or economically feasible. The uncertainty of restoration at sites where complete DNAPL depletion cannot be obtained is a key issue and EPA scientists have focused research on the use of a mass flux-based site management approach to assess NAPL source-zone treatment benefits.